1. Field of the Invention
The present invention relates to a semiconductor package with a heat sink, on which a chip such as an IC chip or LSI chip is mounted.
2. Description of the Related Art
Recent high semiconductor device technology as is apparent from theoretical devices, successively reduces the speed and power product per gate, and the development of miniaturization technology gradually reduces the device-occupying area per gate.
The development of semiconductor chips is apt to achieve higher speed and higher integration. The development of packages for protecting semiconductor chips and improving their reliability is now entering in the region of installment in consideration of the art of bonding semiconductor chips.
Accordingly, various types of semiconductor packages to mount LSI semiconductor devices or a high-density and miniaturized LSI chip have gradually been employed in recent computer systems in order to improve the system performance and reliability.
As the degree of the integration of semiconductor devices increases, the power dissipation of a semiconductor chip rises. In this connection, each LSI chip with high power dissipation is mounted in a package made of ceramics having a greater thermal conductivity than plastic. However, the efficiency of heat dissipation by a printed circuit board alone to cool the LSI chip is naturally limited.
Under such circumstance, in a conventional semiconductor package on which the aforementioned high-speed, high-integration LSI chip is to be mounted, from a viewpoint of a cooling effect to the heat generated by the LSI chip, a heat sink made of a material such as aluminum or copper that has high heat dissipation efficiency is secured integrally on the top of the semiconductor package by solder or an adhesive that has high thermal conductivity to discharge the heat effectively.
FIG. 1 is a perspective view illustrating an example of a conventional heat-sink equipped package, and FIG. 2 is a vertical cross-sectional view of the same. In these diagrams, reference numeral "1" is a case, reference numeral "5" denotes pins and reference numeral "7" is a heat sink.
A chip-mount plate 2 of a material having good thermal conductivity is adhered to the top surface of the case 1. A chip 3 is mounted on the bottom surface of the chip-mount plate 2 by a chip adhesion agent.
The chip 3 is connected to wirings on the case 1 by wiring members 4. A plurality of pins 5 are provided on the bottom surface of the case 1. A cap 6 is adhered to the bottom surface of the case 1 to cover the chip 3, keeping the interior of the case 1 airtight.
The heat sink 7 is adhered to the top of the chip-mount plate 2 by a heat sink adhesion agent. The heat sink 7 has a plurality of rectangular plates of the same shape arranged in a row. Today, packages with such a structure are manufactured.
The heat-sink equipped packages having this structure do not have high heat dissipation efficiency and cannot yield a sufficient cooling effect. This shortcoming leads to a temperature rise of the chip, thus lowering the operation speed of the device.